Belgian Pat. No. 543,080 discloses that alkyl-substituted, heterocyclic compounds can be dealkylated by passing such compounds together with steam over a catalyst containing one or more metals of the 8th group of the Periodic System, and/or compounds thereof, at a temperature of 400.degree.-900.degree. C. When this process disclosure is followed in the demethylation of .alpha.-picoline, by passing .alpha.-picoline together with steam over a catalyst system containing iron oxide at a temperature of 700.degree. C., 30% of the .alpha.-picoline will be converted and only 60% of the converted .alpha.-picoline will be demethylated to produce pyridine. In view of this rather low efficiency, and also in view of the high temperatures involved, this process is economically unattractive for the commercial preparation of pyridine from .alpha.-picoline.
U.S. Pat. No. 3,334,101 discloses the dealkylation of alkyl pyridines with steam at a temperature of 180.degree.-360.degree. C. using a nickel--nickel oxide catalyst containing less than 50% of free nickel. The process of this U.S. Patent offers a considerably lower temperature range than that of the Belgian patent mentioned above, but when applied to the demethylation of .alpha.-picoline, the conversion is considerably lower than that of the aforesaid Belgian patent while the process is only moderately efficient as regards the .alpha.-picoline converted which is demethylated to pyridine. In addition, the regeneration of the nickel--nickel oxide catalyst is extremely difficult.
It will be appreciated from the above, that the prior art has sought a process with reasonable conversion of .alpha.-picoline, and a high efficiency of the converted .alpha.-picoline into pyridine, with a catalyst that has extended process life and can be easily regenerated.